A Closer Look at ACC/AHA and ESC Guidelines for Managing Obesity and Overweight in Adults

The prevalence of obesity worldwide has reached alarming levels, tripling since 1975.¹ In the European Union, around 59% of adults are living with overweight or obesity,² while in the United States, over 40% of adults are affected by this.³ This alarmingly high prevalence is concerning because obesity frequently coexists with cardiovascular risk factors and is associated with a greater risk for cardiovascular disease (CVD).⁴ Our understanding of obesity and its impact on CVD has grown tremendously in recent years, necessitating updated guidelines for its management to mitigate CVD risk. While the 2013 American College of Cardiology (ACC)/American Heart Association (AHA)/The Obesity Society Guideline for the Management of Overweight and Obesity in Adults⁵ provides guidance, there have been several changes in clinical practice since the publishing of this guideline, including the Food and Drug Administration approval of new pharmacotherapies, procedures, and devices for weight loss. Hence, new recommendations are needed from updated guidelines. Fortunately, the 2019 ACC/AHA Guideline on the Primary Prevention of Cardiovascular Disease⁶ and the 2021 European Society of Cardiology (ESC) Guidelines on Cardiovascular Disease Prevention in Clinical Practice⁷ include much needed recommendations on the management of obesity and overweight in adults. This viewpoint compares the American and European recommendations for managing obesity and overweight in adults, highlighting key similarities and differences.

Index of obesity and overweight

Body mass index (BMI) (weight in kg/height in m²) is commonly used to define overweight (BMI 25-29.9 kg/m²) and obesity (BMI ≥30 kg/m²). Both ACC/AHA guidelines recognize that individuals diagnosed with obesity or overweight are at greater risk of CVD. While BMI is recommended to be used as the primary screening tool for weight loss and metabolic health assessment, it has limitations such as not distinguishing between fat and lean body mass or subcutaneous and visceral fat.⁶ Moreover, BMI might not accurately gauge metabolic health in adults with high muscle mass, older adults, and people of Asian descent.⁸ Waist circumference has emerged as a simple and clinically applicable method to assess abdominal adiposity and is strongly associated with all-cause and CV mortality. It is recommended to include waist circumference measurement alongside BMI to better stratify obesity-related health risks^6,7—as visceral fat is independently associated with cardiometabolic and atherosclerotic cardiovascular disease risk.⁹ Waist circumference measurements should especially be obtained in the patients who have central adiposity and/or a BMI of <35 kg/m². Both ESC and ACC/AHA guidelines set thresholds for elevated waist circumference if it is ≥40 inches (102 cm) in men and 35 inches (88 cm) in women. Notably, both guidelines acknowledge that there may be ethnic differences in the association between waist circumference and cardiometabolic risk.⁶

Weight loss in obesity and overweight

Both the ACC/AHA and ECS guidelines recommend weight loss in individuals with overweight and obesity to improve the risk factor profile for atherosclerotic cardiovascular disease.^6,7 A clinically meaningful weight loss is defined as a 5% reduction in body weight, which is associated with improvements in blood pressure, lipid profiles, glycemic control, and even premature all-cause mortality in patients with obesity or overweight. However, ESC guidelines caution that weight loss should not be the primary focus in older adults, as it may be associated with higher mortality, a phenomenon known as the obesity paradox. The ESC guidelines recommend that older adults with obesity or overweight should focus on preserving muscle mass and getting adequate nutrition rather than losing weight, considering uncertainties around the obesity paradox and potential biases like reverse causality.⁷ The ACC/AHA guideline also stresses caution in achieving weight loss in older adults, in order to prevent loss of lean body mass and nutritional deficiencies.⁶

Strategies to ameliorate obesity and overweight

With regard to strategies for ameliorating obesity and overweight, both guidelines agree that comprehensive lifestyle interventions are needed.^6,7

Dietary intervention

Both the ACC/AHA and ECS guidelines recommend some form of calorie-restricted diet.^6,7 The ACC/AHA guideline suggests reducing caloric intake should by 500 kcal/d, with some cases requiring a very-low-calorie diet (<800 kcal/d) under careful medical supervision.⁶ ESC endorses several hypocaloric diets for weight loss including a plant-based, hypocaloric Mediterranean diet, low- or very-low-carbohydrate diets (50-130 g and 20-49 g carbohydrate per day, respectively), low-fat diets (<30% of energy from fat), and high-protein diets. While all of these diets offer similar weight loss in the short term, only the Mediterranean diet renders long-term benefits. Low- or very-low carbohydrate diets—or even the ketogenic diet—can improve glycemic control in diabetes; but they should be plant based and not for long term. High-protein diets can help maintain lean muscle mass and promote satiety, as well as prioritize diets with less refined sugars and healthy food groups such as fruits and vegetables.⁷ The ECS guidelines also approve of intermittent fasting and time-restricted eating, although they do not result in greater weight loss than calorie-restricted diets. More important than any one diet or feeding pattern, though, are the dietary principles to which one adheres. The key dietary principles recommended by ESC include adopting a plant-based diet rich in whole grains, vegetables, fruits, nuts, and fiber-rich foods, while replacing saturated with unsaturated fats, and reducing salts and sugar (especially sugary beverages), and alcohol consumption.⁷ It is important to note that there is no uniform Mediterranean lifestyle or dietary pattern as its adherents live in diverse geographical locations and other diets may be suitable in certain patient populations.

Physical activity

Physical activity is important alongside dietary modifications to maximize the benefit. The ACC/AHA guideline recommends at least 150 minutes aerobic physical activity (eg, brisk walking) per week (equivalent to 30 minutes per day for 5 days of the week) for initial weight loss,⁶ increasing to round 200 to 300 minutes per week to maintain body weight and prevent weight regain. Overall, a comprehensive lifestyle intervention integrating diet and exercise can result in 5 to 10% weight loss and improvement in metabolic health.⁶ The ESC guideline acknowledges the significance of physical activity in managing obesity and overweight but does not provide specific recommendation.⁷ Recent evidence suggests that a combination of aerobic and resistance exercise, along with weight loss, is effective for improving physical and metabolic status in older adults with obesity. Adjustments may be necessary for this population due to challenges such as sarcopenic obesity, and exercise regiments should consider individual preferences and realistic goals.

Pharmacotherapy

In addition to lifestyle modifications, pharmacotherapy can also be used for achieving weight loss. The ESC guidelines endorse medications such as orlistat, naltrexone/bupropion, and high-dose liraglutide,⁷ while the ACC/AHA does not.⁶ Differences in approve medications may exist due to variations in approvals by regulatory agencies.¹⁰ Clinicians should be aware of these differences, considering regional differences. The lack of consensus between guidelines and approved medications may pose challenges in clinical decision-making and may also impact patient access to effective treatments. However, the impact of these medications on obesity-related CVD remains uncertain, although some studies suggest potential benefits for primary prevention. Nonetheless, it is important to note that conclusive evidence regarding the CV outcomes of these treatments in obesity is still lacking, highlighting the need for adequately powered CV safety trials.

Bariatric surgery

The ESC guidelines recommend bariatric surgery for "obese high-risk individuals" when lifestyle changes fail to result in weight loss maintenance.⁷ They emphasize the inclusion of LIFEtime-perspective CardioVascular Disease calculator for predicting lifetime CVD risk, which can help identify high-risk individuals in both the short and long term. This information can aid in clinical decision-making for the management of obesity and associated cardiovascular risks.⁷

Concluding remarks and future perspectives: a viewpoint

Overall, both guidelines highlight the importance of addressing overweight and obesity to prevent CVD. One key difference is ESC guidelines recommend a comprehensive lifestyle intervention that includes dietary modification, increased physical activity, and behavioral support,⁷ whereas the ACC/AHA guidelines recommend a healthy lifestyle that includes counseling, caloric restriction, regular physical activity, and weight management.⁶ The ESC guidelines also provide specific recommendations for weight-loss medications and bariatric surgery in select patients with obesity and high CVD risk,⁷ whereas the ACC/AHA guidelines do not have specific recommendations for these interventions.⁶

However, what is missing from these guidelines? While both the ESC and ACC/AHA guidelines provide recommendations on managing obesity and overweight, there are some areas where they may be lacking. Personalized approaches to weight management and addressing social and environmental determinants of obesity may not be fully considered. Early intervention and addressing childhood obesity are also areas that may require more emphasis. Despite the existence of evidence-based guidelines for managing obesity in adults, implementing lifestyle interventions in routine clinical practice remains a challenge. While randomized controlled trials provide important information about the effectiveness of lifestyle interventions for weight management and are valuable in guiding the guidelines, the programmatic approaches used in these trials may not always be feasible or sustainable in routine clinical practice. For example, lifestyle interventions delivered in academic centers may require significant resources and infrastructure, which may not be available in primary care settings. Thus, there is a need for evidence-based tools that can facilitate weight loss and weight loss maintenance, easily implementable and address the challenges associated with long-term weight management in routine clinical practice. The development and evaluation of such tools should also be a priority for future research in this area.

The future management of obesity and overweight in adults requires careful consideration of various perspectives and directions (Figure 1). Ongoing research on different interventions and development and refinement of guidelines to stay up to date with the latest evidence are needed. Although it is difficult to achieve, individualized approaches to weight management should be prioritized, considering the unique needs of each individual. Additionally, identifying and managing subclinical CVD in this population is important to prevent progression to clinical CVD. Customized interventions targeting diet and physical activity for effective weight management may require a multidisciplinary team of health care professionals, including cardiologists, endocrinologists, obesity-medicine specialists, bariatric surgeons, psychologists, and nutritionists, to provide comprehensive assessments and address the contributing factors to weight gain. By working collaboratively and implementing personalized strategies and utilize practical tools such as digital health technology and evidence-based weight management programs, we can enhance weight management outcomes and reduce CV risk. However, barriers such as limited awareness, inadequate training, and a shortage of resources dedicated to obesity management hinder the successful implementation of guidelines in clinical practice. Overcoming these barriers is essential to equip health care providers with the necessary knowledge, skills, and resources for effective obesity management and improved patient outcomes. Furthermore, addressing disparities in health care access is crucial to ensure equal opportunities for achieving better outcomes for individuals with obesity and overweight. It is worth noting that although there is room for improvement in both guidelines, they play a crucial role in raising awareness and promoting better management for obesity.

Figure 1.

Future Perspectives and Directions in Managing Obesity and Overweight in Adults

Summary of guidance for researchers and clinicians to navigate the evolving field of obesity management and develop successful strategies that can improve the outcome of adults with obesity or are overweight.

Funding support and author disclosures

Dr Nguyen is supported by grants from the National Institutes of Health (R01HL151704 and R01HL159010). Dr Tang served as a consultant for Sequana Medical, Cardiol Therapeutics, Genomics plc, Zehna Therapeutics, Renovacor, WhiteSwell, Kiniksa, Boston Scientific, and CardiaTec Biosciences and has received honorarium from Springer Nature and American Board of Internal Medicine. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.